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Forward photon energy spectrum at LHC 7TeV p-p collisions measured by LHCf

Forward photon energy spectrum at LHC 7TeV p-p collisions measured by LHCf. Hiroaki MENJO (KMI, Nagoya University, Japan) On the held of the LHCf collaboration. RICAP 2011, Roma, Italy, 25-27 May 2011. Contents. Introduction Overview of the LHCf experiment

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Forward photon energy spectrum at LHC 7TeV p-p collisions measured by LHCf

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  1. Forward photon energy spectrum at LHC 7TeV p-p collisions measured by LHCf Hiroaki MENJO (KMI, Nagoya University, Japan) On the held of the LHCf collaboration RICAP 2011, Roma, Italy, 25-27 May 2011

  2. Contents • Introduction • Overview of the LHCf experiment • Forward photon energy spectrum at √s = 7eV proton-proton collisions • Summary LHCf is a LHC forward experiment, which is dedicated for UHECR physics.

  3. The LHCf collaboration The LHCf collaboration K.Fukatsu, T.Iso, Y.Itow, K.Kawade, T.Mase, K.Masuda, Y.Matsubara, G.Mitsuka, Y.Muraki, T.Sako, K.Suzuki, K.TakiSolar-Terrestrial Environment Laboratory, Nagoya University, Japan H.MenjoKobayashi-Maskawa Institute, Nagoya University, Japan K.YoshidaShibaura Institute of Technology, Japan K.Kasahara, Y.Shimizu, T.Suzuki, S.Torii Waseda University, Japan T.TamuraKanagawa University, Japan O.Adriani, L.Bonechi, M.Bongi, R.D’Alessandro, M.Grandi, P.Papini, S.Ricciarini, G.Castellini INFN, Univ. di Firenze, Italy K.Noda, A.TricomiINFN, Univ. di Catania, Italy M.HaguenauerEcolePolytechnique, France W.C.TurnerLBNL, Berkeley, USA J.Velasco, A.FausIFIC, Centro Mixto CSIC-UVEG, Spain D.Macina, A-L.Perrot CERN, Switzerland

  4. Introduction HECRs Extensive air shower observation • longitudinal distribution • lateral distribution • Arrival direction Air shower development Astrophysical parameters • Spectrum • Composition • Source distribution Xmax distribution measured by AUGER PROTON The hadron interaction models used in air shower simulations have an uncertainty due to the lack of experimental data in the energy range over 1015eV IRON

  5. The Large Hadron Collider (LHC) pp 7TeV+7TeV Elab= 1017eV pp3.5TeV+3.5TeV Elab= 2.6x1016eV pp 450GeV+450GeV Elab= 2x1014eV 2014- Key parameters for air shower developments CMS/TOTEM • Total cross section↔ TOTEM, ATLAS(ALFA) • Multiplicity ↔ Central detectors • Inelasticity/Secondary spectra↔Forward calorimetersLHCf, ZDCs ALICE LHCb ATLAS/LHCf

  6. ATLAS 96mm Detector Location LHCf Detector(Arm#1) 140m Two independent detectors at either side of IP1( Arm#1, Arm#2 ) Beam pipe Protons Charged particles(+) Neutral particles Charged particles(-) TAN -Neutral Particle Absorber- transition from one common beam pipe to two pipes Slot : 100mm(w) x 607mm(H) x 1000mm(T)

  7. 32mm 25mm The LHCf Detectors Sampling and Positioning Calorimeters • W (44 r.l , 1.7λI ) and Scintillator x 16 Layers • 4 positioning layers XY-SciFi(Arm1) and XY-Silicon strip(Arm#2) • Each detector has two calorimeter towers, which allow to reconstruct p0 Expected Performance Energy resolution (> 100GeV) < 5% for photons 30% for neutrons Position resolution < 200μm (Arm#1) 40μm (Arm#2) Arm2 Front Counter • thin scintillators with 80x80mm2 • To monitor beam condition. • For background rejection of beam-residual gas collisions by coincidence analysis 40mm Arm1 20mm

  8. η 8.5 ∞ LHCf can measure Front view of calorimeters @ 100μrad crossing angle Energy spectra and Transverse momentum distribution of Projected edge of beam pipe • Gamma-rays (E>100GeV,dE/E<5%) • Neutral Hadrons (E>a few 100 GeV, dE/E~30%) • π0 (E>600GeV, dE/E<3%) at psudo-rapidity range >8.4 Forward region is very effective on air shower development. Multiplicity@14TeV Energy Flux @14TeV High energy flux !! Low multiplicity !! simulated by DPMJET3

  9. Operation in 2009-2010 At 450GeV+450GeV • 06 Dec. –15 Dec. in 2009 • 27.7 hours for physics, 2.6 hours for commissioning • ~2,800 and ~3,700 shower events in Arm1 and Arm2 • 02 May – 27 May in 2010 • ~15 hours for physics • ~44,000 and ~63,000 shower events in Arm1 and Arm2 At 3.5TeV+3.5TeV • 30 Mar. – 19 July in 2010 • ~ 150 hours for physics with several setupWith zero crossing angle and with 100μrad crossing angle. • ~2x108 and ~2x108 shower events in Arm1 and Arm2 Operation at √s = 900GeV and 7TeV has been completed successfully.The detectors has been removed from the LHC tunnels at July 2010, and will be upgraded for the future operations.

  10. Forward photon spectrum at √s = 7eV p-p collisions The paper has been submitted to PLB “ Measurement of zero degree single photon energy spectra for √s = 7 TeV proton-proton collisions at LHC “ O. Adriani, et al. arXiv:1104.5294 CERN-PH-EP-2011-061, Seminar at CERN on 17-May by Prof. Sako is in the archive http://indico.cern.ch/conferenceDisplay.py?confId=137111

  11. Analysis for the photon spectra • DATA • 15 May 2010 17:45-21:23, at Low Luminosity 6x1028cm-2s-1 • 0.68 nb-1 for Arm1, 0.53nb-1 for Arm2 • Analysis Procedure • Energy Reconstruction from total energy deposition in a tower with some corrections, shower leakage out etc. • Particle Identification by shape of longitudinal shower development. • Cut multi-particle events. • Two Psudo-rapidity selections, η>10.94 and8.81<η<8.9. • Combine spectra between the two detectors.

  12. Event sample Longitudinal development measured by scintillator layers 25mm Tower 32mm Tower Total Energy deposit Energy Shape PID 600GeV photon 420GeV photon Lateral distribution measured by silicon detectors X-view Hit position, Multi-hit search. Y-view

  13. Particle Identification • Event selection and correction • Select events <L90% threshold and multiply P/ε ε (photon detection efficiency) and P (photon purity) • By normalizing MC template L90% to data, εand P for certain L90% threshold are determined. Calorimeter Depth Elemag: 44r.l. Hedonic: 1.7λ L90%Distribution dE Photon Hadron Calorimeter layers Integral of dE Calorimeter layers

  14. Multi-hit identification • Event cut of multi-peak events, • Identify multi-peaks in one tower by position sensitive layers. • Select only the single peak events for spectra. An example of multi peak event Double hit detection efficiency Small tower Large tower Arm1 Single hit detection efficiency Arm2

  15. Comparison between the two detector • Psudo-rapidity selection, η>10.94 and 8.81<η<8.9 • Normalized by number of inelastic collisions with assumption as inelastic cross section of 71.5mb • Spectra in the two detectors are consistent within errors. Combined between spectra of Arm1 and Arm2 by weighted average according to errors Arm1 detector Arm2 detector Filled area : uncorrelated systematic error

  16. Comparison between MC’s DPMJET 3.04 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145 One more model, QGSJETII-03 will be added soon. Gray hatch : Systematic Errors Blue hatch: Statistics errors of MC

  17. Next Plans • Ongoing analysis • Energy spectrum of photons in the wider psudo-rapidity range. • PT distribution • Hadron spectra • π0 spectra • Photon and Hadron energy spectra at 900GeV. • Future operations • p-p collisions at the LHC designed energy, √s = 14TeV in 2014. • p-A , A-A collisions at LHC and operations at RICH (Only ideas)

  18. Summary • LHCf is one LHC experiment dedicated for cosmic ray physics. The aim is to calibrate the hadron interaction models which are used in air shower simulations. • LHCf measured photon forward energy spectra in the psudo-rapidity ranges, η>10.94 and 8.81<η<8.9 at √s = 7TeV proton-proton collisions. • We compared the spectra with several interaction models • None of the models perfectly agree with data • Large discrepancy especially in the high energy with all models. • Analysis is ongoing. Results at √s = 7TeV p-p collisions, energy spectra of photon, hadron, PT distributions and etc., will be provided soon and many results from future operations, p-p at 14TeV, p-A also.

  19. !!!! Grazie !!!! !!!! Grazie !!!!

  20. Backup slides

  21. Energy Spectra at 900GeV Arm1 Hadron response under study Hadron like Gamma-ray like preliminary preliminary Only statistical errors are shown Arm2 Hadron like Gamma-ray like preliminary preliminary The spectra are normalized by number of gamma-ray and hadron like events The detector response for hadrons and the systematic error are under study.

  22. p0 reconstruction An example of p0 events measured energy spectrum @ Arm2 25mm 32mm preliminary Silicon strip-X view 1(E1) Reconstructed mass @ Arm2 R 140m  2(E2) I.P.1 • Pi0’s are a main source of electromagnetic secondaries in high energy collisions. • The mass peak is very useful to confirm the detector performances and to estimate the systematic error of energy scale.

  23. Summary of systematic errors

  24. PT distribution for photons  pp 7TeV, EPOS

  25. Front Counter • Fixed scintillation counter • L=CxRFC; conversion coefficient calibrated during VdM scans

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